1. Field of the Invention
This invention relates to a supported catalyst composition for polymerization of 1-olefins, to the preparation of such catalysts, and to a process of polymerizing 1-olefins using such catalysts.
2. Description of the Prior Art
In the polymerization of 1-olefins to produce polyethylene, polypropylene and copolymers, such as ethylene-butene copolymers, considerable effort has been expended to improve catalyst productivity while at the same time achieving a desired set of polymer properties characterized by particle size distribution, molecular weight, molecular weight distribution, and bulk density, characteristics all important in the handling, processing use and storage of the product. Particularly in the production of polyethylene and ethylene-butene copolymers, sensitivity of the catalyst to hydrogen and comonomer are significant in control of the molecular weight and comonomer incorporation to achieve desired polymer characteristics.
Previously, workers in the field have used finely divided porous inorganic oxides, such as silica or silica-alumina, as a catalyst support (for example, see U.S. Pat. Nos. 3,993,588 and 4,452,912) or as a catalyst diluent (U.S. Pat. No. 4,081,589).
In variant syntheses of catalysts, organic acid halides have been mentioned for use as precipitating agents or as electron donors, and chlorosilanes have been reacted with organomagnesium compounds.
More specifically, U.S. Pat. No. 4,328,121 teaches preparation of 1-olefin polymerization catalysts by a method which includes using aluminum alkyls or aluminum alkylhalides as a precipitating agent for a hydrocarbon solution of a titanium alkoxide and a magnesium alkoxide. Organic acid halides, including benzoyl chloride, are among those listed as being suitable precipitating agents.
U.S. Pat. No. 4,420,417 teaches preparation of an ethylene polymerization catalyst by reacting a titanium alkoxide and a magnesium alkoxide in a hydrocarbon solvent with acetylchloride until the solvent phase has no chloride or titanium, after which the by-product ester is removed by distillation and the hydrocarbon suspension is activated by addition of an alkylaluminum halide. Organic acid halides having an alkyl group of 1 to 12 carbon atoms are described as suitable and as generically exemplified by the acetylchloride.
U.S. Pat. No. 4,379,758 teaches preparation of ethylene polymerization catalysts by combining alkylaluminum halide treated particulate silica with magnesium chloride and titanium chloride dissolved in an ether as an electron donor solvent, followed by drying the mixture, then slurrying the dried mixture with a hydrocarbon solvent and reacting the slurried mixture with a boron halide, followed by another drying step and then treatment of the dried boron halide treated impregnated silica with an aluminum alkylhalide. Magnesium diethyloxide is said to be a suitable substitute for the magnesium chloride. Esters of aliphatic and aromatic carboxylic acids are said to be suitable electron donor solvents.
U.S. Pat. No. 4,175,170 teaches the preparation of 1-olefin polymerization catalysts by impregnating finely divided porous silicon dioxide with an aluminum alkyl or aluminumalkylhalide in a hydrocarbon solvent, removal of the solvent to recover the solid phase, combining the solid phase with a magnesium compound in a suitable solvent, recovering the resultant solid phase, combining it with a titanium alkoxy-halide or titanium tetrahalide in a hydrocarbon solvent, then recovering the final solid phase product as the catalyst. Listed among magnesium compounds as suitable are magnesium dihydrocarbyloxides.
U.S. Pat. No. 4,526,941 teaches preparation of 1-olefin polymerization catalysts by reacting a chlorosilane and an organomagnesium compound (typically formed by reacting an alkylmagnesium halide and a trialkylaluminum, but which, it is said, may be a magnesium alkoxide), then combining that reaction product first with an electron donor ester of a nitrogen- or sulfur-containing heterocyclic acid or an ester of a hydrocarbylcarboxylic acid, followed next by a titanium compound, in some instances a titanium alkoxide. Optionally, the organomagnesium compound may be treated with an electron donor (halides and esters of hydrocarbylcarboxylic acids are mentioned) before reacting the product of that treatment with a chlorosilane. The chlorosilane reaction with either the treated or untreated organomagnesium compound may be conducted in the presence of a silica or silica-alumina support.